Membrane potential and conductance during transport of sodium, potassium and rubidium in frog muscle

摘要: 1. Muscles with high intracellular sodium concentrations can extrude into solutions which contain 10 m-equiv/l. of either potassium or rubidium. Potassium rubidium replaces the extruded sodium. These cation movements take place equally well when external anion is chloride sulphate, though muscles deteriorate if left for long periods in sulphate solutions. 2. Measurements potentials during extrusion containing show: (a) an internal potential more negative than equilibrium (EK); at 20° C difference nearly 20 mV. (b) that a between membrane and EK dependent on temperature abolished by 10−5 M ouabain. (c) becomes presence 0·1% cocaine, concentration cocaine substantially increases resistance to movement. In absence no such hyperpolarization occurs. 3. When they have are 10-20 mV extruding corresponding potassium. 4. electrical conductance solution suggest electrochemical ions may be large enough account measured inward extrusion. The reliability measurements does not, however, exclude possibility some part movement chemically linked outward movement. 5. rubidium, net ouabain, lead conclusion least 90% must movement. 6. could explained basis fall region extracellular space immediately membrane. It argued certain characteristics make it difficult explain this alone, due depletion rubidium. The main pump capable transferring electric charge across operating, but that, given time, transferred less has transported, amount corresponds transported pump.